Inverse projection: question about w coordinate

Posted by fayeWilly on Game Development See other posts from Game Development or by fayeWilly
Published on 2014-08-23T11:55:36Z Indexed on 2014/08/23 16:34 UTC
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Filed under:

opengl

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matrix

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transformation

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projection

I have to perform in shader an inverse projection from a u/v of a render target.

What I do is:

Get NDC as
2*(u,v,depth) - 1 Then world space as

tmp = (P*V)^-1 * (NDC,1.0); world space = tmp/tmp.w;

This apparently works, but I am confused about the w division there. Why this work? Shouldn't be a multiplication by a w somewhere (as in the "forward" pipeline there is the perpsective division?)

Thank you,

Faye

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